1) Field of the Invention
The present invention relates to a locking hinge, and more particularly, to an exterior vehicle mirror assembly having a locking hinge for positioning a mirror head on pivotally connected support arms.
2) Description of Related Art
Locking hinges are used in diverse forms for the hinged fixture of rearview mirrors in automobiles. In the simplest form, such a locking hinge contains one first and one second locking arm that end in cooperating, generally identical, locking members. The locking members have cylindrical locking surfaces that face each other and both the locking arms or locking members are pressed and braced against each other with the help of a screw with a spring that goes through both of them.
The disadvantage with this known type of locking hinge is that there is no flexibility whatsoever with respect to the design. Moreover, such locking hinges are relatively big and are characterized by a large weight. Finally, such locking hinges in the above mentioned rudimentary design are visually less attractive.
In addition, there are locking hinges known for automobile exterior mirrors with which the first locking arm is formed by one leg of the mirror, which is joined to the automobile. A primarily horizontally stretched first locking member is provided on the first locking arm. A second locking member of a second locking arm in the shape of a pipe is arranged on the first locking member. Both the locking members are connected to one another with a primarily vertically aligned screw with a spring, and braced against one another. The pipe-shaped locking arm stretches somewhat at right angles to the screw axis. This known form of locking hinge is also characterized by a relatively large construction.
There are other known types of locking hinges, which have one thing in common, which is that they have one or more locking surfaces that are kept under tension with the help of separate screws and/or spring elements.
Locking hinges, especially for the exterior mirrors of utility vehicles are exposed to considerable stresses and loads in daily use. These loads and stresses include force caused by vibrations that are sustained over long periods of time, moderate to medium load forces, particularly by wind, as well as brief and shock type of loads when the exterior mirror held by the locking hinge bangs against an obstacle.
Locking hinges with spring elements that operate as the retention force for holding the assembly together have the disadvantage that in the event of failure of the spring element, for example, breakage of the spring owing to the types of loads mentioned above, the locking hinge can lose its retaining feature or, at least, the retention or holding feature is impaired considerably.
Accordingly, it is an object of the present invention to design a locking hinge and holder arms in such a manner that even in the case of failure of the spring element resulting from a force on the locking hinge, the hinge does not lose its locking connection and retaining features completely.
Further, it is another object of the present invention to provide a lighter weight and visually pleasing design for a locking hinge in an exterior vehicle mirror assembly.